In the high-side switching configuration, the power switch is located between the load and the positive terminal of the battery and controls energy flow by opening or closing the power supply path. The high-side switching configuration offers a unique advantage of protecting against inadvertent load short events in which the load may be short-circuited to ground (i.e., vehicle chassis). Because the power switch is located upstream, a load short does not cause a catastrophic battery short as in the case of the low-side switching configuration.
However, the inventor has found out that, in a conventional high-side metal-oxide-semiconductor field effect transistor (MOSFET), voltage tolerance of the substrate is limited by its structure, and thus performance of a high-side switching configuration is limited. Moreover, a conventional high-side MOSFET has a problem of electric field punching through, and it results in actual performance worse than theoretical yield. With market trend of minimization and demands of high performance at the same time, performance of high-side switching configuration has to be improved.
Accordingly, it is needed to provide a new structure of high-side MOSFET in order to solve the problem of electric field punching through in a conventional high-side switching configuration and also improve voltage tolerance and high-side ability.